ingredients

what is octinoxate?

Daniel Judd BSc MBiol

What is octinoxate?

Octinoxate, also known as octyl methoxycinnamate, is a chemical sunscreen based on the naturally occurring molecule cinnamic acid. As you might have guessed, cinnamic acid comes from cinnamon, although it’s usually chemically synthesised when used on an industrial scale.

Chemical sunscreens are one of two larger groups of sunscreen ingredients, the other being mineral sunscreens like titanium dioxide and zinc oxide.

How does it work?

Like other sunscreens, octinoxate protects your skin from sunburn and skin cancer caused by the sun’s UV rays. Without sunscreen, UVB light can penetrate your skin where it can directly damage your DNA leading to mutations and possibly cancer. The remaining UV light (UVA) causes indirect damage by creating highly reactive free radicals which attack your DNA, breaking it apart. Your body tries to prevent UV damage progressing into cancer by triggering the inflammation response seen in sunburn. As well as being painful, this inflammation damages collagen in your skin, causing wrinkles and prematurely aged looking skin.

When rubbed into your skin, sunscreens create a UV absorbing barrier, stopping the UV rays from getting any further. Octinoxate is good at absorbing UVB but not UVA so it is usually mixed with other chemical and mineral sunscreens to give a wider coverage and protection.

Safety

Side effects:

Like many other chemical sunscreens, octinoxate can trigger allergic reactions in some people causing inflammation and swelling. In some cases the allergic reaction doesn’t occur immediately but instead is triggered when the octinoxate covered skin is exposed to sunlight.

Another common concern with chemical sunscreens including octinoxate is the fear that it may be an endocrine disruptor. That is, once it is inside the body it can mimic estrogen and wreak havoc with your hormonal system. Currently there are a number of tests on cell cultures (cells in a petri dish) and animals that suggest some chemical sunscreens can mimic hormones in this way. What’s missing is information on this effect in live humans and without this information it’s hard to accurately say whether octinoxate or other chemical sunscreens are dangerous in this way.

Interaction with other chemicals:

A study found that octinoxate increased the absorption though the skin of a herbicide called 2,4-dichlorophenoxyacetic acid, an issue for agriculture workers who spend time in the sun while exposed to this herbicide.